This invention relates generally to nut follower devices adapted to engage external threads of a screw, and more particularly to devices of this type which minimize undesirable backlash between the nut and screw, and which compensate for slight misalignments between the screw and the machine part that is adapted to carry the nut.
Specifically, this invention relates to improvements in the applicant's anti-backlash nut illustrated and described in U.S. Pat. No. 3,831,460, issued Aug. 27, 1974.
The device disclosed in the above patent involves a tubular nut body having two elements with internal thread formations which are adapted to engage the external threads of a screw, together with a spring sleeve having four pairs of oppositely disposed transverse slots, wherein each of the adjacent pairs of slots in the sleeve is indexed circumferentially by an angle of 90.degree. with respect to the other. While this device generally operated in a satisfactory manner, in some cases it was desired to provide increased self-alignment capability beyond that which was available from the patented construction. In addition, due to the fact that the spring sleeve has four pairs of slots, there was a tendency for the sleeve to become expanded or compressed when the nut device was subjected to heavy loads. This occurred by virtue of the 90.degree. orientation between each of the adjacent slot pairs. Also, due to the relatively close spacing of the four slot pairs, there was a limitation on the maximum misalignment which could be tolerated, while still providing satisfactory performance and smooth operation.